This invention relates to the disposal of mixed waste which often includes metal oxides, lead and other metals. Mixed waste contains both chemically hazardous constituents, as defined by the Resource Conservation and Recovery Act of 1976 (RCRA), and low-level radioactive waste, as defined in the DOE Order 5820.2A (Sep. 26, 1988), Attachment 2 (May 11, 1988). Low-level waste means radioactive waste not classified as high-level waste, transuranic waste, or spent nuclear fuel as defined by the Order.
The scope of this document is limited to low-level radioactive waste which may not contain more than 100 nCi/gm of transuranic radionuclides (TRU). Wastes containing &gt;100 nCi/gm are classified as TRU wastes and will be disposed of at the Waste Isolation Pilot Plant (WIPP). The 100 nCi/gmm limit applies to the final waste form. The treatment and disposal of mixed wastes must adhere, as a minimum, to the relevant provisions of the RCRA, the Atomic Energy Act of 1954, as amended, and state requirements, as mandated by the Federal Facilities Compliance Act of 1992 (FFCA).
Previously, sulfur polymer cement has been used for construction purposes and is made by reacting sulfur with dicyclopentadiene (DCP) and oligomers of cyclopentadiene (OCP). The problem with this material is that both DCP and OCP are very reactant and the attributes of their reaction products are sensitive to various processing variables. This results in batch to batch variation for sulfur polymer cement (SPC). Because SPC has demonstrated excellent resistance to salts and acids, it is a product which may be useful for the encapsulation for mixed wastes including low level toxic metal oxides and radioactive wastes.
The subject invention combines sulfur and the thermoplastic material having a melting temperature less than about 150.degree. C. and low level radioactive wastes or toxic metal oxides to provide a solid material which has very good performance in the Toxicity Characteristics Leach Procedure Test (TCLPT). Compared to the DCP standard, the inventive material is only slightly less effective, on the order of about 25% but is significantly cheaper and provides repeatable results.